1. Field of the Invention
The present invention relates to an electronic part and a circuit substrate.
2. Description of the Related Art
With the recent improvement in the performance of computer systems, numerous electronic parts having various functions are mounted on a single circuit substrate and when an electronic part requires replacement due to failure or the like, or when a new electronic part is added to expand function, replacement work or addition work of the electronic part on the circuit substrate is necessary. In such a case, a hot plug (hot swap) mechanism is required when a desirable part must be replaced or added in a state in which a part of the circuit substrate is kept alive while another part of the circuit substrate is not.
FIG. 11 is a perspective view of an electronic part and a circuit substrate that implement a conventional hot swap mechanism. FIG. 12 is a partial cross-section of an electronic part and a circuit substrate that implement the conventional hot swap mechanism. As shown in FIG. 11, a plurality of wirings 402 to 404 are formed on a main surface 401 of a plug-type connecting terminal 400. The wirings 402 to 404 are arranged to have different distances from a connecting end 405 in the direction of electrical connection (direction indicated by outlined arrows in FIG. 11). Moreover, a plug portion 510 having a hollow rectangular cross-section is formed on a main surface 501 of a receptacle-type connecting terminal 500. On an inner peripheral surface of the plug portion 510, a plurality of wirings 502 that are arranged to have the same distance from a connecting end 505 are formed.
When the connecting terminals 400 and 500 thus arranged are connected, upon plugging the plug-type connection terminal 400 into the plug portion 510 of the receptacle-type connecting terminal 500, the wirings 402 that are arranged at both ends in a direction perpendicular to the direction of the electrical connection and the wirings 502 are connected first, the wirings 403 and the wirings 502 are connected next, and the wirings 404 and the wirings 502 are connected finally. When the plug-type connecting terminal 400 is unplugged from the plug portion 510, the wirings are disconnected in the opposite order. Such a structure is referred to as card-edge connection.
On the other hand, in an electronic part 600, a plurality of electrical connecting terminals 601 to 603 that are different in height (having different lengths) from a main surface 604 in an inserting direction (direction indicated by outlined arrows in FIG. 12) are formed and arranged two-dimensionally, as shown in FIG. 12. Moreover, in a circuit substrate 700, electrical contactors 702 are formed on inner peripheral surfaces and peripheries of holes 701 to which the electrical connecting terminals 601 to 603 are inserted. With such a structure, higher integration and higher density can be achieved compared to the above card-edge connection, and also in this structure, when the electronic part 600 is plugged into to the circuit substrate 700, the electrical connecting terminal 601, the electrical connecting terminal 602, and the electrical connecting terminal 603 are sequentially connected to the electrical contactors 702. When the electronic part 600 is removed from the circuit substrate 700, the terminals are disconnected in the opposite order. Such a structure is referred to as a pin grid array (PGA).
In other words, in the hot swap mechanism of conventional connecting structures such as the card-edge connection shown in FIG. 11 and PGA shown in FIG. 12, by forming parts corresponding to one of the connecting parts (wiring or connecting terminal), which are connected to each other, in different lengths (wiring length, etc) in the direction of electrical connection, the hot swap mechanism is implemented in which contact timing of the respective parts is varied. With this arrangement, replacement or the like of electronic parts in a state in which, for example, wirings of a power source and a ground are kept alive while a wiring of a circuit is not (for example, Japanese Patent Laid-Open Publication No. H10-41025).
There still are some problems with the hot swap mechanism described above. For example, in the card-edge connection, the wirings 402 to 404 can only be formed on the main surface 401, which is on only one of the two sides of the plug-type connection terminal 400. In PGA, to maintain strength, the electrical connecting terminals 601 to 603 cannot be formed at intervals smaller than certain intervals in the electronic part 600, in other words, there is a limit in terms of high density mounting.
Therefore, to achieve further high density mounting, mounting techniques such as a ball grid array (BGA) and a land grid array (LGA) have been developed, which enable electrical connection between an electronic part and a circuit substrate with electrodes formed at 0.5 millimeter (mm) intervals. However, in BGA and LGA, once electrical connection with the circuit substrate is established, connectors such as an electrode bump and an electrode land are mechanically connected to each other permanently. Therefore, this mounting technique is not suitable for part replacement or the like (For example, Japanese Patent Laid-Open Publication Nos. 2000-340709 and 2001-68594).
Therefore, electrical connection of an electronic part and a circuit substrate in which part replacement or the like can be easily done has been achieved by arranging deformable spiral contactors on the circuit substrate while maintaining correspondence with the electrode shape in BGA and the like. FIGS. 13A to 13C and FIGS. 14A to 14C are action transition diagrams for explaining electrical connection between an electronic part and a circuit substrate using conventional spiral contactors. First, as shown in FIG. 13A, in an electronic part 800, a plurality of spherical electrical connecting terminals (electrode bumps) 801 to 803 are formed. Moreover, in a circuit substrate 850, a plurality of planar spiral contactors 851 to 853 are formed at positions corresponding to connecting positions with the electrical connecting terminals 801 to 803.
As shown in FIG. 13B, if the electronic part 800 is gradually brought close to the circuit substrate 850 in the direction of the electrical connection (direction indicated by the outlined arrow in FIG. 13B), each of the electrical connecting terminals 801 to 803 comes into contact with each of the spiral contactors 851 to 853 at substantially the same time. Then, as shown in FIG. 13C, each of the spiral contactors 851 to 853 deforms in the direction of electrical connection (direction indicated by an outlined arrow in FIG. 13C), thereby securely connecting each of the electrical connecting terminals 801 to 803 and each of the spiral contactors 851 to 853.
Furthermore, as shown in FIG. 14A, in an electronic part 900, a plurality of planar electrical contactors 901 to 903 are formed. In a circuit substrate 950, a plurality of convex spiral contactors 951 to 953 are formed at positions corresponding to connecting positions with the electrical contactors 901 to 903. As shown in FIG. 14B, if the electronic part 900 is gradually brought close to the circuit substrate 950 in the direction of the electrical connection (direction indicated by the outlined arrow in FIG. 14B), each of the electrical contactors 901 to 903 comes into contact with each of the spiral contactors 951 to 953 at substantially the same time. Then, as shown in FIG. 14C, each of the spiral contactors 901 to 903 deforms into a planar shape, thereby connecting each of the electrical contactors 901 to 903 and each of the spiral contactors 951 to 953 securely (for example, Japanese Patent No. 3440243).
In the electrical connection of the electronic part and the circuit substrate shown in FIGS. 13A to 13C and FIGS. 14A to 14C, the electrical connecting terminals 801 to 803 (901 to 903) and the spiral contactors 851 to 853 (951 to 953) come into contact at substantially the same time. Therefore, although an attaching/detaching mechanism of the electronic part 800 (900) and the circuit substrate 850 (950) is implemented, a hot swap mechanism in which, for example, after a power circuit in the electronic part 800 (900) is energized, energizing of a predetermined circuit is difficult to implement together with the attaching/detaching mechanism.
In addition, for high integration and high density, it is difficult to implement both the attaching/detaching mechanism of the electronic parts and the hot swap mechanism at the same time in a chip size package (CSP) technique, such as BGA and LGA. The techniques disclosed in the patent documents mentioned above do not provide a technique that achieves the attaching/detaching mechanism of the electronic parts and the hot swap mechanism at the same time, either.